I don't know about the others, but the reason QED sandalwood soap is a little more expensive than the other QED soaps is that it is scented only with pure genuine sandalwood EO. Even AOS, which prides itself on using only EO's, doesn't make this claim for its sandalwood cream.
The stuff is pretty expensive, so most manufacturers use a fragrance oil which is a synthetic close simile of the real deal, but as you've noticed, not quite. Others, like AOS and others, do use real sandalwood, but it is blended with something else.
Hope this helps?
If you REALLY are curious, go to a natural foods store, and look for pure sandalwood oil. Should be in a tiny tiny bottle for a really not so tiny price, and take a whiff of the sampler.

John P.